This invention relates to a broadband signal amplifier having at least a partial pole-zero compensation, more particularly to a broadband signal amplifier which comprises feedback means.
A broadband signal amplifier of this type is known from EP-A 0,314,218, which corresponds to U.S. Pat. No. 4,872,209 (Oct. 3, 1989) and is suitable for use in, for example, measuring apparatus, communication apparatus, medical apparatus, high-definition television circuits, circuits for color graphic display devices and computer monitors, and, for amplifier circuits for amplifying signals sampled at high sampling frequencies in digital apparatus.
The known broadband signal amplifier comprises, inter alia, a transimpedance amplifier having a low-ohmic current input and an output from which an output voltage can be derived. The transimpedance amplifier is negatively current fed back to the low-ohmic current input so that specific resonant frequencies produced by parasitic capacitances in the transfer function of the transimpedance circuit acquire a higher value and the bandwidth is increased. The broadband signal amplifier also comprises a transadmittance circuit connected to the input of the transimpedance amplifier. The bandwidth is further increased by suitably compensating the first-order decrease of the transfer function of the transimpedance amplifier with a first-order increase of the transfer function of the transadmittance circuit.
A drawback of the known broadband signal amplifier is that the use of the current control requires a powerful driver which is generally adjusted in class A and which dissipates a lot of energy, while a possible adjustment in class B requires many electronic components in the driver.